Problem: Simplify the following expression: $5\sqrt{27}$.
Answer: First, try to factor a perfect square out of the radical. $= 5\sqrt{27}$ $= 5\sqrt{9 \cdot 3}$ Separate the radical and simplify. $= 5\sqrt{9} \cdot \sqrt{3}$ $= 5 \cdot 3 \cdot \sqrt{3}$ $= 15\sqrt{3}$